Who pays Child Maintenance and who is it for?

Things have got rather chaotic in the last few weeks between DP and DSD mum regarding money- the written agreement they had regarding financial support for DSD while she is at College broke down within days and DSD has been struggling to feed herself/wash her clothes while she's away due to lack of money.

In the course of discussion, it became apparent that DSC mums resents the fact that DP doesn't give her enough to live on. DP asked her to explain and it seems that DSC mum expects DP and myself to fund the lifestyle she wants to have, in addition to supporting the DCs. She was very clear "what about MY things?" "Why won't you give me more money?"

I admit I'm a bit gobsmacked. It certainly explains the resentment and anger she feels towards DP and myself as she feels I have cheated her out of her money - but I'm not sure if there is anything DP and I can do to allieviate that. It was a clean break divorce and she applied for maintenance via the CSA the day DP moved out rather than discuss finances in mediation - but she's been harbouring resentment for 5 years because she isn't receiving spousal maintenance. (As an aside, she's always been the higher earner, so I'm not sure she'd even be awarded maintenance in court, would she?)

ihear Yes, DP has spoken to DSD, yes, she does want to change to our address - it was while she was telling her mum that (she asked DP to be there because she was scared of Mums reaction) that all DSD mums resentment about spousal maintenance came out!

DSD has already started to make changes to records at College and they'll be in touch soon to assess the bursary - but her Mum still refuses to discuss it; keeps repeating to DD and DP, "I don't agree, so it's not happening".

Why, oh why won't she just talk about it? This is going to be really messy.

It will be messy but then it always was going to be. There isn't a thing you can do to change the fact your DSD is at a point in her life where she has to make selfish decisions that affect others, when she has the right to make those decisions. This was always going to happen, it's just happening sooner than your DP's ex had thought/hoped/expected.